The present invention is directed to the cooling of molds in a glassware forming machine, and more particularly to liquid cooling of the blank molds and/or blow molds in an individual section machine.
The science of glass container manufacture is currently served by the so-called individual section machine. Such machines include a plurality of separate or individual manufacturing sections, each of which has a multiplicity of operating mechanisms for converting one or more charges or gobs of molten glass into hollow glass containers and transferring the containers through successive stations of the machine section. Each machine section includes one or more blank molds in which glass gobs are initially formed in a blowing or pressing operation, an invert arm for transferring the blanks to blow molds in which the containers are blown to final form, tongs for removing the formed containers onto a deadplate, and a sweepout mechanism for transferring molded containers from the deadplate onto a conveyor. U.S. Pat. No. 4,362,544 includes a background discussion of both blow-and-blow and press-and-blow glassware forming processes, and discloses an electropneumatic individual section machine adapted for use in either process.
In the past, the blank and blow molds of a glassware forming machine have generally been cooled by directing air onto or through the mold parts. Such techniques increase the temperature and noise level in the surrounding environment, and consume a substantial amount of energy. Furthermore, productivity is limited by the ability of the air to remove heat from the mold parts in a controlled manner, and process stability and container quality are affected by difficulties in controlling air temperature and flow rate. It has been proposed in U.S. Pat. Nos. 3,887,350 and 4,142,884, for example, to direct a fluid, such as water, through passages in the mold parts to improve heat extraction. However, heat extraction by liquid cooling can be too rapid and uncontrolled, at least in some areas of the mold, so steps must be taken to retard heat transfer from the inner or forming surface of a mold part to the outer periphery in which the liquid cooling passages are disposed. Various techniques for so controlling liquid-coolant heat extraction have been proposed in the art, but have not been entirely satisfactory.
U.S. application Ser. No. 09/400,123, filed Sep. 20, 1999 and assigned to the assignee hereof, discloses a system and method for cooling the forming molds in a glassware forming machine, in which each mold includes a body of heat conductive construction having a central portion with a forming surface for shaping molten glass and a peripheral portion spaced radially outwardly of the central portion. A plurality of coolant passages extend in a spaced array around the peripheral portion of the mold body, and liquid coolant is directed through such passages for extracting heat from the body by conduction from the forming surface. A plurality of openings extend axially into the body radially between at least some of the liquid coolant passages and the forming surface for retarding heat transfer from the forming surface to the liquid coolant passages. The openings have a depth into the mold body, either part way or entirely through the mold body, coordinated with the contour of the forming surface and other manufacturing parameters to control heat transfer from the forming surface to the coolant passages. The openings may be wholly or partially filled with material for further tailoring heat transfer from the forming surface to the coolant passages. The mold body is constructed of austenitic Ni-Resist ductile iron having elevated silicon and molybdenum content. Endplates are carried by the mold body for controlling flow of coolant in multiple passes through the coolant passages. The mold may be either a blank mold or a blow mold.
U.S. application Ser. No. 09/513,049, filed Feb. 24, 2000 and assigned to the assignee hereof, discloses a system and method of cooling glassware molds by directing liquid coolant to the blank or blow mold halves of a glassware forming machine through an enclosed pivotal rotary union-type structure. A cooling manifold is carried by each pivotal mold arm, and communicates with coolant inlet and outlet ports at the lower end of each mold part. The manifold is connected by a floating shaft seal, a rotary union assembly and a crank arm to a coolant source and a coolant return in the section box of the associated machine section. Each pivotal connectionxe2x80x94i.e., between the section box and the crank arm, between the crank arm and the rotary union assembly, and between the rotary union assembly and the floating shaft sealxe2x80x94comprises a bi-directional rotary union for feeding liquid coolant to the manifolds and mold parts, and returning coolant from the manifolds and mold parts. Dynamic floating seals between the coolant manifolds and the mold parts, and between the coolant manifolds and the rotary union mechanisms, accommodate relative motion between these components as the mold parts are opened and closed.
Although the systems and methods for cooling molds in a glassware forming machine disclosed in the noted applications address problems theretofore extant in the art, further improvements remain desirable. In particular, it is desirable to remove all fluid hoses and other fluid coupling mechanisms external to the mold arms. The liquid coolant flows at elevated temperature, and it is highly desirable to reduce potential damage and leaks in the coolant flow path under the harsh environmental operating conditions of a glassware forming system. Molten glass, abrasive glass particles and spent lubricants can cause damage to the hosing, tubing and rotary fittings. The hoses, tubing and fittings can become loosened or fatigued due to the harsh operating conditions and severe vibration forces during normal operation, and impede rapid maintenance, repair and replacement of the mold parts and operating mechanisms. It is therefore a general object of the present invention to provide a system and method for cooling either the blank molds or the blow molds in a glassware forming machine, in which the coolant flow passages are entirely enclosed within the machine components, and protected from abrasion and fatigue under the harsh operating conditions of a glassware forming system.
Briefly stated, the presently preferred system and method of the invention direct liquid coolant to the blank or blow mold parts or halves of a glassware forming machine by means of source and return coolant passages that extend through a hinge post on which the mold arms are mounted, and through the mold arms to and from each mold part. In the preferred embodiments of the invention, a manifold is carried beneath each mold arm, and the coolant passages in the mold arms extend through the manifold to and from the respective mold parts. A system for cooling molds in a glassware forming machine in accordance with the present invention thus includes a pair of mold arms mounted on a hinge post for movement toward and away from each other, and at least one mold part carried by each mold arm and adapted to cooperate with each other to form a glassware blank mold or blow mold. Each mold part includes at least one liquid coolant passage having an inlet and an outlet disposed at one end of the mold part, and each mold arm has inlet and outlet coolant flow passages operatively coupled to the inlet and outlet of the mold part mounted on that arm. A liquid coolant source and a liquid coolant return are disposed in fixed position adjacent to the hinge post. A first coolant passage extends through the hinge post between the coolant source and the inlet flow passages in the mold arms, and a second coolant passage extends through the hinge post between the outlet coolant flow passages in the mold arms and the coolant return. Thus, liquid coolant flows in a closed path from the source through the hinge post and the mold arms to the mold parts, and from the mold parts back through the mold arms and the hinge post to the return.
The hinge post preferably includes an elongated cylindrical portion on which the mold arms are pivotally mounted. Both of the first and second coolant passages include a first portion that extends axially within the hinge post, and a second portion that extends radially to a circumferential face of the cylindrical portion of the hinge post. The inlet and outlet coolant flow passages in the mold arms include portions in axial registry and radial alignment with the second portions of the first and second coolant passages for delivering coolant from and to the hinge post independent of pivotal position of the mold arms on the hinge post. Seals are carried by the mold arms in sealing engagement with the circumferential face of the cylindrical portion of the hinge post in the preferred embodiments of the invention to seal the second portions of the first and second passages from each other. Bearings are carried by the mold arms in engagement with the circumferential face of the cylindrical portion of the hinge post, which preferably is hardened and functions as an inner race of the bearings. Thus, the internal volume of the hinge post in the preferred embodiments of the invention is entirely available to formation of the fluid flow passages that extend through the hinge post.
The hinge post has a lower end portion that is secured to a mold support bracket or other suitable fixed structure on the section box of each machine section. This lower end portion of the hinge post preferably is of tapering conical construction and is self-centering in the support bracket. The hinge post may be either secured to the support bracket and the mold arms removably mounted from the hinge post, or the hinge post and mold arms may be removable as an assembly from the mold support bracket. The coolant fluid source and return may be secured to the lower axial end of the hinge post, or may be coupled to the hinge post by means of fluid passages in the mold support bracket.